An automatic residual line suppression system for use with a spread spectrum signal wherein a narrow-band sample of the signal around a selected frequency is multiplied by a dithered signal in an auto-balance control loop. A resulting signal is used to control the dc offset of a mixer in order to minimize...http://www.google.com/patents/US4479227?utm_source=gb-gplus-sharePatent US4479227 - Auto-balance method and apparatus for suppression of residual lines in a transmitted spectrum
